The present invention concerns a device and process for measuring and regulating the pressure of at least one tire fitted on a vehicle wheel.
From the prior art, in particular from the document EP-B1-0 671 998, a device is already known for measuring and regulating the pressure of a tire fitted on a vehicle wheel, of the type comprising a source of compressed air, an air feed circuit that connects the said source to the tire, and pressure measurement means in the circuit or in the tire.
In the remainder of this description the circuit will be regarded as extending from the air source towards the tire. Thus, “upstream” refers to a part of the circuit which is closer to the air source and “downstream” to a part of the circuit closer to the tire.
The feed circuit generally comprises a check valve which opens when the pressure in the circuit exceeds the pressure in the tire by a predetermined value.
When the tire is fed with air by a device of the above type, the pressure in the circuit or in the tire is generally unstable. Inasmuch as the pressure is unstable, it is difficult to measure the pressure in the circuit or in the tire exactly. To avoid this problem it has therefore been proposed to measure the pressure of a tire by the following procedure:                the circuit is fed with compressed air so as to open the check valve and place the circuit and the inside of the tire in fluid communication,        the compressed air feed is stopped,        stabilization of the pressure in the circuit and tire is awaited, and        the pressure in the circuit or tire is measured.        
This process enables a precise measurement of the pressure in the tire to be obtained during its inflation, but entails frequent stopping of the compressed air feed. The process is therefore particularly lengthy and restrictive.
Moreover, with this tire pressure measurement process, each time the pressure in the circuit is measured some air is injected into the tire, and this increases its pressure. Thus, too many pressure measurements risk increasing the tire pressure abnormally.
The purpose of the invention is to overcome pressure instability problems so as to enable more precise regulation of the pressure in the tire.